Process of constructing variable condenser rotors



M l 1927' c. P. POWE-RS PROCESS OF CONSTRUCTING VARIABLE CONDENSER ROTORS Filed Aug. '7 1925 Patented Mar. 1, 1927.

UNITED STATES PATENT OFFICE.

CHARLES PRIOR POWERS, OF SPRING LAKE, NEW JERSEY, ASSIGNOR TO U. S. TOOL COMPANY, INC., 01 EAST ORANGE, NEW JERSEY, .A CORPORATION OF JERSEY.

PROCESS OF GONSTBUCTING VARIABEE CONDENSER BOTOES.

Application filed August 7, 1925. Serial No. 48,909.-

This invention relates to radio apparatus and particularly to condensers, with special reference to the rotor and stator plates used in connection therewith.

5 It is essential in obtaining the greatest eihciency in condensers that the stator plates be in positive electrical contact, one with another, so that no resistance effects and especially loss of energy can occur.

plates be similarly connected to present a substantially homogeneous solid construction in which current conduction is positively assured.

One of the objects of the present invention is, therefore, to overcome the difliculty heretofore experienced in making metallic connections to aluminum by providing a rotor in which all of the several plates are electrically joined to their intervening separator elements or directly to each other to constitute a rotor having a solid hub.

A further feature is in the provision of a process whereby condenser plates of aluminum orv other metal are caused to cohere, at their portions circumjacent their axis, in a novel and practical manner, positively assuring full conductivity.

Another aim is to provide a process broad- 1y applicable in electrically connecting any series of adjacently arranged aluminum plates, along their edges causing them to tenaciously adhere without distortion of the plates or in any way injuriously affect the appearance of physical properties of the metal.

These'objects are attained by the process and in the manner hereinafter described and indicated in the accompanying drawing,

40 constituting part of this disclosure, and in which Figure 1 is a side elevational view of one form of a rotor plate.

Figure 2 is a similar view of the same,

showing a slightly modified form of hub.

Figure 3 is a side view of a rotor spindle showin an assembly of spaced plates engaged t ereon.

Figure 4. is a fragmentary longitudinal sectional view, taken, on the center line of the spindle, drawn to an enlarged scale and illustrating part of the process.

Figure 5 1s a fragmentary transverse sec- It is equally necessary also that the rotor A tional view taken on the line 55 of Fig ure 4.

Figure 6 is a still tional'view showing the results attained by the process.

Figure 7 is a side view of a spacing element as disposed between contiguous plates.

Condensers manufactured inthe usual manner are known to have high electrical resistance between the parts, due to poor contact therebetween. Such high resistance develops because of oxidation or corrosion of the surfaces, which increases with the passa e of time, and it is also known that electrical difficulties are present, due to galvanic action between the parts.

It is of prime importance in the manufacture of condensers to minimize these resistance conditions, as low resistance tends to ensure an eflicient condenser, resultin in sharper tuning and cater intensity 0 signals, which is technically expressed by the term, low phase angle.

further enlarged sec- In condensers of the better grade it is preferred to use sheet aluminum for both thestator and rotor plates, such plates being light in weight, cleanly in appearance, easily constructed and having good conducting properties. 1

Means have been developed whereby the stator lates may be formed from a single plate, ie cut and bent to present an integral structure of any number of leaves, such being the subject matter of a previous patent.

As it is not readily feasible to construct the rotor plates in the same manner, ways have been devised to obtain an essentially solid construction which will now be described.

Referring in greater detail to the drawing, the numeral 10 desi ates any one of a series of rotor plates, which, irrespective of their contour, ordinarily presents a hub 11 containing an opening 12, here shown polygonal to fit the correspondingly shaped portion 13 of a spindle 14.

The milled portion 13 of the spindle is provided with, a fine screw thread and engaged on it are nuts 15 and 16 clamping theseries of plates therebetween. I

Placed between adjacent plates are metallic spacers 17, which ma be simple punched washers of uniform thic ess, or the spacers may be composed of wire rings, formed in a helical coil, cut, flattened and closed, either wholly or partially, as shown in Figures 5 and 7, these spacers having openings freely engageable over the threaded portion 13 of the spindle and their outer diameters being substantially equivalent in radius to the semi-circular hub portions 11 of thestator plates. v

Itis contemplated to provide narrow open spaces in the spacers 17, as at 21, and the plates 10 may be either flattened slightly, as at 22, or contain notches as at 23, these spaces and notches being eventually filled with alloy to present a smooth finished article.

Before assembling the spacers they may be treated, when in a thoroughly clean condition, to a thin, uniform coating of pure tin, by depositing the same electrolytically as in ordinary plating, by dipping in a bath of molten tin, or by any other method known in the art.

The surfaces of the plates 10, whether of aluminum or other metal. are also rendered chemically clean, and the spacers whether tinned or merely cleaned, placed in position as they are strung on the polygonal portion 13 of the spindle 14, and the nuts 15 and 16 adjusted to firmly clamp the several parts in intimate relation.

If desired. a block having a plurality of parallel slots, one for each plate, may be provided to act as spacing guides and also to carry off heat that may be trans mitted to the plates, thus exposing only their hub portions.

Thereafter heat, as from an electric current, and of such intensity as to cause tin to soften. is applied and when in this clamped, heated condition a block of pure tin is forced over the exposed edges of the plates, in the manner of an abradant, under sufficient pressure to cause the tin by friction to fill any cavities that may exist, as at 19, and form a film 20 over the surface.

Following this an alloy bar 18, see Figures 4 and 5, is forced under considerable pressure and moved reciprocatively across the edges the friction thus engendered, in addition to the heat transmitted to the structure to bring about. proper solvent conditions, as the effect of an autogenous weld, solidifying the plates at their hubs with the spacers in a thorough manner.

The proportions of tin and zinc used may be varied in accordance with the hardness of the joint, about equal quantities by weight being preferred.

Although the heating means described refers to that produced by an electric current, this is not essential in carrying out the process, as the parts may be heated in an oven, muflle or gas flame as may be most convenient. i

It will be noted that the flow of the molton tin serves to unite the plates to produce eflective conductivity, also that no flux or chemicals of any kind are employed in the process.

Although the foregoing is descriptive of the process in its preferred manner, it will be apparent that minor changes may be made therein Without the exercise of invention or conflicting with the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. The process of uniting a series of aluminum plates along their juxtaposed edges which consists in clamping the plates together, heating the plates to at temperature suflicient to melt tin, abrading 'the edges of the plates with a block of tin frictiona-lly applied under pressure, raising the temperature of the clamped plates, and abra'ding the tinned edges with a block of tin and zinc alloy applied frictionally under pressure.

2. The process of autogenously uniting a plurality of aluminum plates having metallic spacers therebetween, which consists in rendering the plates and spacers chemically clean. clamping the plates and spacers in firm intimate relation, heating the clamped plates and spacers to a temperature of sub stantially 230 degrees eentigrade, rubbing the exposed edges of the plates with pure tin under a pressure to cause particles of the tin to adhere to the edges of the plates, raising the temperature to approximately 400 degrees centigrade, rubbing the tinned edges with an alloy of tin and'zinc in substantially equal portions, under heavy pressure until the parts have coalesced, and allowing the united body to cool while clamped.

In testimony whereof I have signed my name to this a plication.

CHA LES PRIOR POWERS. 

